Process for reacting a diolefin and a furfuraldehyde and resulting products



3 Sheets-Sheet l RODUCTS 48 HOURS 20 HOURS EACTING A DIOLEFIN AND A E AND RESULTING P /70 HOURS J. C. HILLYER ET AL PROCESS FOR R 'FURFURALDEHYD FURFURAL BUTADIENE COPOLYMERIZATION 20 TO 70 HOURS TEMP 260F July 6, 1954 Filed March 14, 1949 INVENTOR. J. c. HILLYER D.A. N ICEWANDER BY ATToRNEYs WEIGHT PER CENT OF CHARGE 3o 40 BUTADIENE CONCENTRATION y 1954 J. c. HILLYER ET AL 2,683,151

PROCESS FOR REACTING A DIOLEFIN AND A FURFURALDEHYDE AND RESULTING PRODUCTS Filed March 14, 1949 Patented July 6, 1954 UNITED STATES ATENT OFFICE PROCESS FOR REACTING A DIOLEFIN AND A FURFURALDEHY DE PRODUCTS AND RESULTING Delaware Application March 14, 1949, Serial No. 81,413

21 Claims.

The present invention relates to a process for the inter-reaction of a diolefin and a furfural.

This invention relates also to various products of such inter-reactions. This application is a continuation-impart of our forfeited .copending application Serial No. 746,816, filed May 8, 1947, which itself is a continuation-in-part of our forfeited copending application Serial No. 647,178,

filed February 12, 1946.

When furfural is maintained at elevated temperatures for more or less extended periods of time, dark colored tarry polymers of Very high molecular weight are formed. These substances are indefinite in composition and properties, and have no known commercial value. It is known that furfural in the presence of unsaturated hydrocarbons forms dark colored tarry furfural poylmers which may be dried or oxidized to form a solid polymeric material. This polymer is soluble in furfural and in acetone, but is of little, if any, commercial value.

We have found that a diolefin such as 1,3-butadiene and its immediate homologues may be reacted with a furfural such as furfural itself and its immediate homologues, in the presence of water to produce new products including aldehydes and lactones, which have a polycyclic structure. Since these polycyclic products are generally produced in a mixture'also containing polymers of *butadiene, polymers of furfural, and other complex materials of a polymeric nature, and since their chemical identities were originally unknown, the terms polymers and cc-polymers have been loosely applied to the novel polycyclic chemical compounds disclosed and discussed herein, as well as to tthese other polymeric materials. In view of the identification of certain of these materials .as definite chemical'compounds, as discussed herein, the use cf the term polymers tends to be misleading and the products are more accurately defined as polycyclic reaction products. When reacting 1,3- butadiene with furfural, one of the major reaction products is a pale yellow or amber colored oil, in marked contrast with the tarry mass referred to hereinbefore. The crude oil apparently is a somewhat complex mixture of various reaction products. It has a boiling range of from about 290 F. to about 320 F. under a pressure of about one millimeter of mercury absolute. The refractive index at 77 F. ranges from about 1.520 to about 1.530 and the specific gravity at 68 F. ranges from about 1.08 to 1.16. The average molecular weight was determined as about 210. The physical properties of various fractions of 2 the oil vary somewhat within the indicated boiling range. The average refractive index at 77 F. is about 1.526 while the average specific gravity at 68 F. is about 1.12.

In the fractional distillation of the oil produced by the process of this invention, various fractions may be obtained as products of the process. The physical properties of the products may thus be varied somewhat by separating the oil into fractions having various boiling point ranges. For example, fractions of different viscosity may be obtained by fractional distillation to produce on the one hand an oil of low viscosity and on the other, an oil of high viscosity or one having a slurry-like consistency. The aldehydic content is variable depending on conditions used, in general the content is between 40 and 80 mol per cent, but under suitable operating conditions almost any value between zero and per cent can be obtained. We have found, for instance, that the product distilling near the upper end of the boiling range is generally very low in aldehyde content. By pentane extraction of a lower boiling fraction on the other hand, a product of very high aldehydic content is obtained.

The degree of unsaturation of the fractions is also influenced to some degree by reaction conditions, such as temperature and time of treatment.

The characteristic nature of our unique products gives them numerous potential uses. Among these may be included their use as components in phenolic resins, plasticizers, tackifiers for synthetic rubber, and the like, as intermediates for the syntheses of numerous organic chemicals, such as by condensation of other reactive molecules with either the unsaturated portion of the molecule, the aldehyde group of the aldehyde products, or the potential carboxyl group of the lactone products, or for other uses which will become apparent to one skilled in the art.

An object of our invention is to produce useful products by the reaction of 1,3-butadiene and furfural.

Another object of our invention is to produce useful products by the reaction of a diolefin with furfural, or a homologue thereof.

Another object of our invention is to produce useful products by the reaction of a diolefin with furfural, or a homologue thereof in the presence of water.

Still another object of our invention is to produce polycyclic aldehydes.

Still another object of our invention is to produce polycyclic lactones.

A further object of our invention is to produce useful products from the inter-reaction of a butadiene and a furfural in the presence of water.

Other objects and advantages of our invention will become apparent, to one skilled in the art, from the accompanying disclosure and discussion.

Fig. 1 of the drawings illustrates graphically the yield of polymer, or reaction product, produced from furfural and 1,3-butadiene using amounts of butadiene varying from to weight per cent of the monomer charge. The yield is expressed as parts by weight per 100 parts of furfural charged to the reaction zone.

Fig. 2 of the drawings illustrates graphically the effect of reaction time on the polymer, or reaction product, yield obtained from 1,3-butadiene and furfural in varying proportions. Yield is expressed as parts by weight per 100 parts of furfural charged to the reaction zone.

Fig. 3 of the drawings illustrates possible reaction products which might be obtained from 1,3-butadiene and furfural to produce a polycyclic aldehyde. The probabilities of these vari ous reactions is discussed in greater detail hereinafter in connection with Example III.

As a diolefin reactant in our process, we prefer to use a conjugated diolefin, preferably a conjugated diolefin having not more than about seven carbon atoms per molecule. Such a diolefin can be referred to as a member of the group consisting of 1,3-butadiene and its immediate homologues and may be reported as having the formula where each R is of the group consisting of hydrogen and an alkyl group having not more than three carbon atoms and at least two R, are hydrogen. The furfural reactant employed in the practice of our invention can be referred to as one of the group consisting of furfural and its immediate homologues having not more than seven carbon atoms per molecule. such a material may be said to be a compound having the formula II II R O C where each R is of the group consisting of hydrogen and methyl and at least one B is hydrogen. The more commonly used reactants are 1,3-butadiene and furfural, isoprene and furfural, and piperylene and furfural, and the corresponding diolefins with methyl furfural. It appears that in producing an aldehyde reaction product, two molecules of the diolefin react with one molecule of the furfural reactant by a modification of the Diels-Alder reaction. Also produced are lactones, resulting from union of one molecule of the diolefin with one molecule of the furfural and with one molecule of water.

' As will be discussed in more detail hereinafter, the aldehyde reaction products include compounds having the empirical formula where x is an integer not greater than 2 and y is an integer not greater than 4. These aldemercury, which corresponds hydes probably have the following structural formula HC=O where each R is of the group consisting of hydrogen and methyl and at least one is hydrogen, and each R, is of the group consisting of hydrogen and an alkyl group having not more than three carbon atoms with the sum of the carbon atoms in the R'j/m and in the Rn in each case, not greater than three and at least two of the Rm and of the R M, are hydrogen.

The lactone reaction products include compounds having the empirical formula Gel-11203 A preferred mode of operation of our invention may be illustrated with a reaction system comprising furfural of approximately five per cent water content by weight and butadiene in concentrations from three to fifty per cent by weight. The system is charged to an autoclave and maintained at temperatures within the range of from about 200 F. to about 300 F. for from about 5 to about 190 hours. The reactant product is then removed, unchanged reactants stripped off, and the higher boiling portion fractionated under reduced pressure. Butadiene dimer, which may also be formed in an appreciable amount when temperature and butadiene concentrations are sufficiently high, distills at 97 F. under an absolute pressure of 23 mm. of mercury and, is removed in the stripping process. Our novel products are contained in the fraction distilling from about F. to about 320 F. under an absolute pressure of about one mm. of to about 450 to about I00 F. when converted to boiling temperatures at 760 mm. of mercury absolute. The major fraction of this material distills overhead between and 275 F., under one mm. of mercury pressure.

While the above mentioned ranges of temperature, water content, and diolefin concentration represent conditions under which we generally prefer to operate in the production of our unique compositions, they are not to be construed as limiting in nature, in all instances. Obviously a certain interdependence exists among these variables such as for example, where it is desired to reduce operational time, the temperature, diolefin concentration, or both, should be increased. In general, alteration of any variable will usually require corresponding adjustments in one or more of the interdependent variables if efficient operation is to be maintained.

Pressures are, in general, not critical and while effective conversion is usually obtained at the pressures normally generated at the operating temperature, they may be varied to any desired level such as by admission of nitrogen or other inert gas. It is preferred to have the reactants present in the reaction zone primarily in liquid phase.

The water content of the furfural used in some commercial extractive distillation units, such as those operating on butylene-butadiene separation, is usually about five weight per cent. Although anhydrous furfural may be successfully employed to produce the polycyclic aldehyde, the presence of water in furfural, particularlyat a concentration near this value, is notdetrimental to the operation of this embodiment of our invention. In'fact, water appears to have some catalytic efiect on the reaction of butadiene with furfural to produce our novel aldehyde product 6, total reaction mixture. The copolymer, or reaction product, is expressed in terms of weight per cent of the furfural charged to the system.

The eiTect of varying concentrations of butadiene in the monomer charge is shown in Fig. 1. While increased concentration gives an almost proportional increase in production of our polymeric product, there is a substantial formation of" butadiene dimer with higher concentrations and enters into the reaction which produces the and this generally constitutes a limiting factor lactone. However, water present in furfural in due to economic considerations, usually at or a concentration exceeding from 10 to 20' er cent l w about 50 per ent b t di n by wei often accelerates a secondary c nde tion t The relation of time to conversion rate is shown form undesirable tarry substances which conin F a Depletion of utad y d a ut taminate the aldehyde product, reducing its yield, 45 hours is fii y great to du e the p- When water is present in the butadiene-furfural Parent a of conversion a d stitut nts a reaction mixture lactone ty e compounds, hav- Influencing factor in t of p rat on. ing the empirical formula as discussed herein- By the methods f our invention we are able above, are formed as an additional pr d ct to obtain ultimate yields of our product amount- High temperatures, above about F" may ing to 80 per cent or more b weight based on also accelerate such secondarycondensations as n' l reacted. already described and should be avoided. While The followlng examples illustrate a good quality pro-duct'can be obtained at rela, tors influencing the reaction products produced tively low temperatures, operations below about malor amounts Whlle these 3x55313165 i 160 F. usually require substantially extended elude only the reaction of lig'butadlene Wlth timefurfural, it is to be understood that these are The reaction appears to take place catalytical; considered to be typical reactions and reaction 1y as We as non catalymcauy Thus when products, illustrating the generic feature of our ploying commercially available reactants it has Invention as alsewhflare f In been found that various cuprous salts in minor these examples and 111 other dlscusslon herein, quantities tend to act as inhibitors, as discussed boflmg temperatures subatm?pherlc pres" in some detail in our copending application Sesures have n converted to bolhng tempera rial No. 636,283, filed December 20' 1945, now tures at an absolute pressure of 760 mm. of mero. s. Patent 2,475,094, issued July 5,1949. Howw in accordance with Chem, ever, we have also found that greater quantities page 322 (1946)- of these materials have an opposite effect and HAMPLE I actually promote the reactionsi Other inhibiting agents include mercaptobenzothiazole, as dis- A mixture of freshly steam distilled, new furclosed in our copending application Serial No. fur-a1 containing 4.6 weight per cent butadiene 624,048, filed October 23, 1945, now U. S. Patent and 5.0 weight per cent Water was reacted in 2,473,750, issued June 21, 1949. Water and acids, t el bomb at 260 F- for a p d of 96 hours. both organic and inorganic, also tend to hav This material was transferred to a hash fitted catalytic influence on the reactions With a Vigreux column and distilled under vac- Distillation of the product under reduced presl The data Obtained during s d stillasure is preferred, usually below five mm. of mer tlOn re oted be ow n Table I.

' Table I DISTILLATION DATA ON SAMPLE 1 0 0 h a? Volume 1133 Pres- 3, V61 ea roduct Fraction Distilled, Tempersure, s tf 7 i mmHg 760 mm Grams Percent 7.0 78 25 245 I 20.0 84 5 310 50. 0 121 6 350 546. 0 9s. 5 450.0 120 5 355 475.0 180 5 430 F. D. 25s 5 530 1 iii 5 5 1.0 284 4 575 Residue s 16. 0 2: 7

cury absolute, since substantial losses through secondary condensations, pyrolytic decomposl tion and the like usually result from the higher temperatures required forfractionation at atmospheric pressure.

The curves shown in theedrawings are based upon the data obtained by carrying out the re action between furfural containing about five per cent water by weight andsubstantially'pure 1,3-butadiene. 'The butadiene concentration is expressed in terms of weight per cent oi?v the Fraction 1 comprises the furfural, any oils, and butadiene dimer. Fraction 2 is considered to contain primarily the light polymer, or reaction product and also contains some furfural. It had a specific gravity at F. of 1.131 and a refractive index measured at 68 F. of 1.5283. Fraction 3 was dark in color, had a specific gravity of 1.11 and on standing turned very dark in a few hours. Fraction 2 is discussed further hereinafter. This distillation was discontinued before the high boiling or heavy polymer was distilled overhead.

EXAMPLE II Freshly steam distilled furfural containing five per cent by weight of water was charged to a steel reaction vessel. Sufficient 1,3-butadiene ous fractionations attempts to distill this material at pressures of 0.5 mm. of mercury resulted in decomposition. Fractions 3 through 6 and the residue may be. considered to be the total H m ,4. was added to give a butadiene concentration of 5 t fi' s O1 QJgP Q z fi gg thls 4.0 per cent in the reaction mixture. The comg i n asls f i P position of the charge material was cen 0 e o Ion 9 was e amber colored hqllld. designated as light reac- Parts by Welgh: tion product. Approximately four per cent of Furfuljal 10 the total product distilled in a higher range and Butadlene the remainder or thirty-one per cent of the total Water product formed, was coke. Light products are The temperature within the reaction vessel was fi ed s t at material boiling above the furmaintained at 260 F. for '70 hours. The reaction fural plateaus nd d ll n b low 260 F. at 0.5 product was then transferred to a specially dem o mercury, W ch p dS o 6 0 F- at signed distilling flask and stripped of water and 760 mm. of mercury. Heavy product is defined unreacted furfural and butadiene under a presas that distilling above 260 F. at 0.5 mm. of sure of from two to five mm. of mercury. A resimercury, and coke as that portion not distillable due containing some furfural and the furfuralwithout decomposition under the pressures of 0.5 butadiene condensation products was transferred mm. or above. to a flask vearing a Vigreux column and frac- The data given in Examples I and II on the tionated at pressures in the range O.5-0.2 mm. nature of the reaction product indicates that the of mercury. The data observed during this dislight reaction product, which makes up the bulk tillation are tabulated in Table 11 below: of the material formed, falls essentially on a Table II P cluctD T Kettle Press 0.11. r0 til 15 SD Gt Refractive Cm N)" Y mm. g 2 Temp, at 25 C. 385 3 F cc. gins. 113 1.5 09 370 5.0 115 1.5 101 375 10.0 110 1.5 370 20.0 119 1. 5 103 380 30. 0 1.5 05 308 40.0 121 1. 5 102 380 50. 0 127 2. 0 105 372 50.0 2.0 105 373 70.0 142 2. 0 105 572 00. 0 2. 0 105 372 99. 0 220 2.0 105 372 0.0 220 1.0 105 300 8.0 230 1.0 145 440 9.0 225 2.0 450 0.0 234 2.0 100 480 1.0 230 2.0 200 400 2.5 235 2.0 205 500 3.2 245 2.0 219 515 4.4 242 1.8 213 513 5.2 258 2. 0 222 522 10. 0 255 1.0 215 545 0.0 250 1. 0 225 555 10.0 255 1.0 225 555 0.0 320 0. 5 255 525 10.0 325 0.5 200 030 0.0 0 342 0.5 270 545 Residue a In the above distillation, fraction 1 comprises recovered furiural. Fraction 2 represents the transition between iurfural and the light reaction product and is a mixture of the two. Fraction 3 was an amber colored liquid and is typical of the light reaction product or polymer. The first few milliliters of this fraction were slightly low-boiling and were probably contaminated with a little furfural. Fraction 4 can be regarded as the heart-cut of the light reaction product. Fraction 5 15 similar to fraction l. Fraction 6 comprised the so-called heavy polymer, or reaction product. It consisted of a mixture of white crystals and a red viscous liquid. The crystals which appeared in fraction 6 had a melting point (crude) of 245 F. to 250 F., a melting point after crystallization of 276 F. and an acidity of 0.0 per cent, an aldehyde content of 0.0 per cent, and a molecular weight of about 189. They were insoluble in pentane and soluble in acetone, water, benzene, methanol, cyclohexane and carbon disulfide. The residue was very dark material resembling coke and was not distillable. Both in this case and in the previ- 7 group of compounds.

plateau that appears to have the characteristics of a single chemical compound. In addition the heavier fraction appeared to contain one and possibly two other individual chemical com pounds. The white crystals obtained in this higher boiling fraction represent another probable chemical entity and it seems likely that the red oil which distills within a relatively narrow range at this point is also another compound or Since material balances have fairly well established that two mois of butadiene condense with one mol of furiural to produce this low boiling polymer, and it been isolated in relatively large quantities, attempt was made to determineits chemical nature.

Some early tests on samples of this material isolated in small quantities indicated that it had a molecular weight of approximately 200 or a little more, and that it apparently contained considerable free aldehydes. Specific investigation of the samples of relatively pure materials was carried out on the products of distillation of Examples I and II. In Example 1, fraction 2, which had a boiling range corrected to 760 mm.

pressure of 580-550 F., was selected as typical of the light reaction product and subjected to further study. Molecular weight determinations by lowering of the freezing point of benzene yielded a value of 207. A carbon and hydrogen analysis was made on this material by combustion. All material unaccounted for in this determination was assumed to be oxygen. Results of the analysis were: 75.0 weight per cent carbon; 8.1 weight per cent hydrogen; and 16.9 weight per cent oxygen (by difference). On the basis of a molecular weight of 207, the empirical formula was calculated to be C12.9H16.6O2.2. Titration of the material with standard sodium hydroxide in methanol solution using phenolphthalein indicator showed a slight acidity. This calculated to be 3.07 weight per cent as furoic acid. A portion of the material was analyzed for the presence of an active aldehyde group by treatment with hydroxylamine hydrochloride reagent. On the basis of a molecular weight of 207, the material calculated to be 70.3 weight per cent aldehydes. Fraction No. 3 which boiled at somewhat higher temperature and turned dark on standing was subjected to molecular weight determination and a value of 223 was obtained.

In Example II the first sample examined was fraction No. 3. This material had an initial boiling point, corrected to 760 mm, of 460 F. However, the portion from 35 per cent to 100 per cent overhead boiled within the range of about 5-10522 F. (corrected). It should be noted at this point that reading of pressures on the simple mercury manometer was not accurate to better than 0.5 mm. and this affects considerably the correction of observed temperatures to 760 mm. Analysis of fraction 3 by the hydroxylamine hydrochloride reagent showed aldehyde content .of 80.0 per cent. The fraction was subjected to crystallization in pentane solutions at temperatures of -1l2 F. After two recrystallizations at this temperature, the crystals were examined. The propertiesdetermined in the usual molecular weight, carbon and hydrogen, aldehydes, and physical property tests are tabulated below.

Specific gravity 1.10at 77 F. Refractive index 1.5254 at .68 F. Molecular weight 210.

Empircal formula (from carbon and hydrogen analysis)- C13.3H17.1O2.o. Aldehyde content 99.0%.

Similar determinations were carried out on fraction 4, which had an apparent boiling range of -545-555 F. corrected to 760 mm. pressure. The same statement with regard to the pressuretemperature correction applies in this case. The results of tests made on this material are listed in the following tabulation:

Specific gravity 1.13 at 68 F.

Refractive index 1.5265 at 68 F.

Molecular weight 208.

Acidity 0.82% (calculated as furoic acid).

Aldehyde content 83.5%.

liberated from it with dilute acid. Although a typical crystalline aldehyde addition product formed, this method of purification was not suitable for the small amount of material available. Tests were made on the higher boiling material in fraction No. 6. Information on the results of this investigation are given in a subsequent section.

The molecular weight and empirical formulas determined for these fractions confirm the earlier estimates for material balances that the product consists of the condensation product or two mols of butadiene and .one of furfural. It shows also the rather surprising result that a free aldehyde group is still presentin the molecule, and that very little acid has been formed.

Consideration of the chemical nature of the compounds involved made it seem likely that a Diels-Alder type condensation was occurring in which the olefinic bonds of furfural were sufficiently activated by the presence of the aldehyde group to allow condensation in this manner with the butadiene. Although it is not too surprising that this occurred on the 2.3 position it did seem unusual that this condensation would also occur in the L5 position. Compounds formed by this mechanism would have the empirical formula C13H15O2 and a molecular weight of 204, which agrees closely with the values obtained in the study of the light reaction products. It is also conceivable that after condensation of the first molecule of butadiene with the 2.3 position on the furfural, the second mol of butadiene might condense with the six-membered ring so formed. Or, the first condensation, following the unlikely course of condensation with the L5 position might then result in a product which would undergo further condensation with this six-membered ring. These products were considered less likely than the first mentioned condensation product. It was also surprising that the intermediate product resulting from the condensation of the first mol of .butadiene and furfural was not found. Although it would be expected to have a lower boiling point, it should be distinctly higher than that of .furfural and butadiene dimer and appear in appreciable quantity. No indication of any more than trace amounts of an intermediate compound have been found.

The material has been substantially characterized by its physical properties and has been clearly shown to be an aldehyde by means of the prod uction of the crystalline sodium bisulfite compound. and the formation of an oxirne, small portions of which were'separated as crystalline material during the course .of studies on the titration with hydroxylam'ine reagent. A sufiicient quantity of the copolymer was prepared to enable isolation of the pure compound, and preparation and isolation of a number of its derivatives to complete the identification, particularly to aid in the choice between the possible formulas.

EXAMPLE III To the above end several large portions of the light reaction product were prepared by reaction in large steel bombs in a new apparatus constructed especially for the purpose. The operations were carried out at 260 F. for periods of approximately hours and the materials were isolated from the excess furfural. When sufficient had been obtained the product was .distilled.

Two fractions were prepared and subjected to study. The first, comprising about 100 cc. of the light reaction product of very narrow boiling range is identified as preparation A. The second comprising about 250 cc. of product boiling over somewhat greater range (220260 F. 0.5-1.0 mm.) was identified as preparation B. Both these materials were insoluble in water, dilute sodium hydroxide, and dilute hydrochloric acid solutions. They were decomposed by concentrated sulfuric acids. Both absorbed bromine, reacted with sodium bisulfite and hydroxylamine, and on heating with strong acids or alkalis did not form resins.

These two fractions were redistilled in a small silvered laboratory column constructed especially for the close fractionation of small amounts of material. From the close boiling fraction A, a distillate from 1 per cent to 90 per cent overhead was collected at a temperature of 239.0 F. at 1.1 mm. of pressure. A sample of B was also fractionated in the same still. A slightly larger initial fraction was discarded, but the amount boiling from about 10 to 85 per cent had precisely the same distillation temperature as the fraction obtained from sample A. These overhead fractions were pale yellow liquids having the following properties and analysis:

Boiling point, 700 mm 584.6 F Specific gravity, 1168 1.120. Refractive index, m h".-. 1.5240 Iodine number 253. Acetyl number 0. Solubility:

Water Insoluble.

Dilute NaOH Insoluble.

Dilute HO1 Insoluble.

Concentrated H2804 Decomposes. Qualitative tests:

Flammability l Positive.

Bromine absorption Positive.

Tollens reagent Positive.

Heating with strong acid or alkali No resin formation. Analysis:

Calcd for Found raHreOz Carbon, percent 76.10 76. 45 Hydrogen, percent 8.03 7. 84 Molecular weight 205 204 This material was then used for the preparation of derivatives. Since the oxime had been noted in the earlier tests with hydroxylamine hydrochloride it was prepared, isolated and purified. The compound was white, had a melting point or 206.5-207.5 F. The analysis of the product was: carbon, 71.46 per cent; hydrogen, 7.88 per cent; and nitrogen 6.51 per cent. Calculated values for the oxime C13H17O2N are: carbon, 71.2; hydrogen, 7.82; and nitrogen, 6.38. The sodium bisulfite addition product was also prepared, crystallized, separated from solution and recrystallized.

These two derivatives served to characterize the material as an aldehyde, 013111602. Two additional derivatives were prepared. The 2.4-dinitrophenyl hydrazone was made by a standard reaction. This compound was a yellow, crystalline v derivative melting at 307-308 F. It analyzed carbon, 59.35; hydrogen, 5.3 and nitrogen, 14.3. Calculated values for the product C19H2005N4 are carbon, 59.3; hydrogen, 5.25; and nitrogen, 14.68. The material was also oxidized with alkaline silver oxide, and yielded white crystals of an acid. This compound melted at 195-196 F. analyzed: carbon, 71.01; hydrogen, 7.55; against a calculated value of CIIZHIGOS of carbon 70.90, and hydrogen 7.27.

The fraction from which this material was isolated by further laboratory distillation was an essentially pure compound. The fraction boiling above 85 or 90 per cent respectively represented for the most part column holdup rather than high boiling residue.

The .possible courses of reaction are indicated in the structural formula given in Fig. 3.

Furfural may first react with 1 mol of butadiene according to either reaction (1) or (2) to form the products (A) or (B), depending upon which side of the molecule first reacts. Product (A) is believed most likely. A third possible course of the reaction is indicated by the dotted arrow in reaction (3). Condensation across the oxygen atom is known to occur between furan and ethylene, but the resulting product with butadiene, having the 7 membered oxygen-containing ring fused to the 5 membered oxygen-containing ring seems highly improbable from structural standpoints. Either product (A) or product (B) of the 1 to 1 mol condensation may then react with a second mol of butadiene by reaction (5) or (6) respectively, to yield a product (II) containing the furan nucleus in the middle of the three-ring condensate. The reaction of butadiene to form dimer indicates that it may behave as a diene or as a monoolefin condensing essentially with itself so that formation of products (I) and (III) by the reaction (4) from intermediate A or reaction (7) from intermediate B is also possible. Both compound (I) and compound (III) would be expected to undergo resinification with acid, or particularly, with alkali heating treatment. Since no such resinification was observed, it appears that Formula II is the correct one. This compound may be named 2,34,5bis(A butenylene) tetrahydrofurfural.

EXAlVIPLE IV In the preparation of the large quantities of the low boiling reaction product, a relatively large amount of the high boiling fraction was also obtained. This material was a reddish oil containing some crystals. After standing for a period of months, the material contained a considerable portion of crystals. Fourteen grams of this material boiling at 260-290" F. at 0.5 mm. was redistilled at 0.5 mm. in a 6- inch packed, silvered column. Approximately 1.0 gram of the light reaction product was separated followed by 2.0 grams of a white crystalline solid. The remaining overhead product was a heavy oil. The residue was transferred to a very small flask, but no further crystalline products could be distilled and no crystals separated from the oily overhead material.

The crystalline material was found to melt at 267-268 F. It had a neutralization equivalent of 192. An initial determination of the molecular weight, determined in benzene by the freezing point, was 180, though difiiculty was experienced with low solubility. Determination by the East camphor method gave a value of 158. The material is soluble in water, alcohol, and dilute sodium hydroxide solution. Preliminary carbon and hydrogen analyses gave C, 64.18%; 117.33%; and O, difierence 28.44%. The neutralization equivalent indicates the presence of one potential carboxyl group per molecule.

Further experimental work, described in Examples V and VI of this specification, was undertaken to identify this crystalline material more accurately.

furfural with 1,3-butadiene and water, of the type described in Example IV, after purifica- 163.5 and the molecular weight was 158 by benzene freezing point lowering. The bromine number was 86 gins/100 gms.

By tests which were carried out, it was established that the crystalline product is non-aldehydic, is not a ketone, contains no free car-boxy group, and does not react to phenol tests. cold water solution neutralizes sodium hydroxide slowly and reacts more rapidly when heated. It dissolves slowly in sodium bicarbonate solution upon standing. Hydrolysis of the compound does not give two fragments which precludes the possibility of its being an ester. Thus it is established that a lactone group must be present. Isolation of a pure sample of the hydrolysis product was impossible, a further proof of the lactone structure, it being well known that the hydrolysis products of lactones are usually unstable except in solution.

Carbon-hydrogen analyses indicated an empirical formula of Cal-I40, and, based on the molecular weight data, a molecular formula of CsHmOs. It should be noted that the summation of the atoms of butadiene, furfural and water is also C9H12O3. By hydrogenation over a palladium catalyst, it was established that one and only one unsaturated linkage exists in the compound. Another sample of the material was reacted with acetic anhydride to form an ester, thereby establishing the presence of a hydroxyl group. Dehydration of the compound with phosphoric acid gave good yields of phenyl propionic acid.

EXAMPLE VI Anhydrous furfural containing 3.6 weight per cent butadiene was maintained in a closed reaction vessel under a pressure of from p. s. i. g., at 260 F. for 72 hours. The resulting reaction mixture was distilled under vacuum at one mm. of mercury until a kettle temperature of 212 F. was reached, to remove unreacted furfural and butadiene, butadiene dimer and any other low,- boiling materials. Unreacted butadiene amounting to 1.2 weight per cent of the original butadiene-furfural charge (33 per cent of'butadiene originally charged) was recovered as an overhead distillation product. Butadiene-furfural condensate product amounting to 3.2 weight per cent of the original furfural-butadiene charge, and contaminated with a trace quantity of furfural polymer, was recovered as distillation kettle product.

EXAMPLE VII A series of tests was made to determine the eifect of such variables as water concentration, contact time and temperature on the ratio of light product to heavy product and coke formed.

The effect of water concentration on the type of product formed was studied .by reacting approximately 400 cc. of steam distilled new furfural in steel bombs at 260 F. with the addition of various percentages of water. After the material had been reacted the desired length of time, it was transferred to a laboratory column and fractionated at reduced pressure. .A division between light and heavy products was made as above stated at 260 F. and 0.5 mm..of mer- 10 The 14 cury. The results of this test are tabulated be low in Table IV. I

Table IV EFFECT OF WATER CONCENTRATION ON TYPE OF REACTION PRODUCT Concentration in Reactor Charge Product Formed Hours at 260 F. h Water Wt Butadiene 5 g g uc Percent Wt. Percent Percent Percent As water concentration was increased from 3.8 to the very high level of 29 per cent, the ratio of light product to heavy product and coke formed was decreased very markedly.

EXAMPLE VIII 7 Table V EFFECT or CONTACT TIME ON TYPE or REACTION raopuor ooncenmb Products Formed taiin of Butaone in re- Light Heavy g g gi ggg Products, Products,

Wt. Percent Wt. Percent Hours at 260 F.

UIQUDO combo As might possibly be expected, longer contact times in steel bombs at the elevated temperature appeared to increase the relative amount of heavier product and coke formed with a corresponding decrease in the light product recovered. Further reaction of the original light product would, of course, produce this cheat.

Similar studies were made of the reaction product obtained from runs made at 230 and 260 F., respectively, with varying amounts of the butadiene in which the reaction products, butadiene dimer, and unreacted butadiene were determined. In the run at 230 F. the total product from the bomb. having. an initial butadiene content of 25.0 per cent was distilled after the 70 hour reaction period. The distillation indicated 5.6 weight per cent of heavy product and 94.4 per cent of, the desired light product. In the run .at 260 F., distillation of the product from the initial charge containing 25 per cent butadiene after 70 hours yielded a final product containing 18.8 per cent heavy product and coke and 81.2 per cent light product. The products from the charge containing an initial 50 per cent butadiene on the other hand, analyzed 75.3 weight per cent light product and 24.7 per cent heavy product and coke. The indications derived from these three distillations is that a greater proportion of the total reaction product produced .is in the desired light range when operating at lower temperatures and that excessive amounts of butadiene tend to increase the amount of heavy product and coke somewhat. However, the concentration of. 25

15 per cent butadiene is relatively high and it will be noted that at both temperatures studied a large proportion of the material produced was in the desired boiling range.

EXAMPLE LX Three parallel experiments were carried out employing conditions similar to those of Example II. Butadiene was added in a concentration of 9.7 per cent by weight of the total charge. The reaction vessels were opened at the end of 20, 4'7 and 70 hours, respectively, the contents removed, stripped of butadiene dimer and unchanged reactants and fractionated under reduced pressure to remove the small quantities of high boiling tarry material formed. Yields of the yellow light oil, in parts by weight per 100 parts of butadiene charged, were as follows:

Time Yield 20 hours 15.2 4''! hours 30.0 '70 hours 37.0

The yields of purified product, as parts by weight per 100 parts of the total initial charge, were as follows:

20 hours 1.48 70 hours 3.59

The yields of the purified product obtained at 20 and '70 hours were 85 weight per cent and '75 weight per cent, respectively, of the total unpurified product which was recovered.

EXAMPLE X Desired Prodduct, Parts by Wt. per 100 Parts of Butadiene Charged Time, Hours at 260 F.

The yield of the desired product at 70 hours was 5.7 parts by weight per 100 parts of total charge to the reactor. Substantially all of the remaining butadiene was recovered unreacted or in the form of dimer.

EXAMPLE XI A sample of furfural containing 5 weight per cent water and weight per cent butadiene based on total reactor charge was heated in a steel reaction chamber for 70 hours at a temperature of 230 F. Unchanged reactants and butadiene dimer were stripped after which the higher boiling portion was fractionated under reduced pressure. A yield. of 30.8 parts of purified product by weight per 100 parts of butadiene charged was obtained under these conditions. The weight of desired product was 95 per cent of the total weight of unpurified product obtained. Substantially all the remaining butadiene was recovered either as such or as the dimer.

It will be appreciated that many modifications and variations of our process may be made, based upon the disclosure and discussion contained herein, without departing from the spirit or scope thereof, and without departing from the scope of the claims.

We claim: 1

1. 23,4,5 bis(A butenylene) tetrahydrofurfural substantially free from other compounds formed during its preparation.

2. An aldehyde substantially free from other compounds formed during its preparation and having the formula where each R is of the group consisting of hydrogen and methyl and at least one is hydrogen, and each R is of the group consisting of hydrogen and an alkyl group having not more than three carbon atoms with the sum of the carbon atoms in the Rm and in the R in each case, not greater than three and at least two of the R'm and of the R'n are hydrogen.

3. A process for producing an aldehyde having the formula where each R is of the group consisting of hydrogen and methyl and at least one is hydrogen, and each R. is of the group consisting of hydrogen and an alkyl group having not more than three carbon atoms with the sum of the carbon atoms in the R'm and in the R'n in each case, not greater than three and at least two of the R'm and of the R'n are hydrogen, which comprises reacting a mixture consisting essentially of a furfural having not more than seven carbon atoms per molecule and the formula where each R. is of the group consisting of hydrogen and methyl and at least one is hydrogen, and a conjugated diolefin hydrocarbon having not more than seven carbon atoms per molecule and the formula where each R is of the group consisting of hydrogen and an alkyl group having not more than three carbon atoms and at least two are hydrogen, under reaction conditions such that two molecular proportions of said hydrocarbon react with one molecular proportion of aldehyde reactant, and recovering from efiiuents of said reaction a fraction comprising said aldehyde product.

17 4. A process for preparing H2 H H 30 nn Ht t H-C=O which comprises reacting a mixture consisting essentially of furfuraldehyde and 1,3-butadiene at a reaction temperature not greater than about 300 F'., and recovering from products of said reaction an aldehyde fraction comprising said compound.

5. A. process for the production of a reaction product of 1,3-butadiene and furfuraL. which comprises reacting a mixture consisting essentially of 1,3-butadiene and furfural, and recovering from eifiuents of said. reacting a. material comprising a polycyclic compound containing a furan ring and at least one six-membered carbocyclic ring and. containing a carbonyl radical attached to a carbon atom of said furan ring adjacent the oxygen atom thereof.

6. The process of claim 5 in which said fraction recovered comprises an aldehyde having the empirical formula C1sI-I1sO2.

7. A process for the production of a reaction product of a conjugated diolefin and a furfural, which comprises reacting a mixture consisting essentially of a conjugated diolefin having not more than seven carbon atoms per molecule and the formula RI R! R! RI H t=t t=tH where each R is of the group consisting of hydrogen and an alkyl group having not more than three carbon atoms per molecule and at least two are hydrogen, and a furfural having not more than seven carbon atoms per molecule and the formula where each R is of the group consisting of hydrogen and methyl and at least one is hydrogen, and recovering from effluents of said reacting a prod uct fraction comprisinga polycyclic compound containing a furan ring and at least one six membered carbocyclic ring and containing a carbonyl radical attached to a carbon atom of said furan ring adjacent the oxygen atom thereof.

8. The process of claim 7 in which said product fraction comprises an aldehyde having the empirical formula where each x is an integer not greater than 2 and each 11 is an integer not greater than 4.

9. A process for the production ofa reaction product of 1,3-butadiene and furfural, which comprises causing 1,3-butadiene to interact with furfural in the absence of a catalyst and at a temperature in the range of 160 to 300 F., said furfural containing water in a concentration below per cent by weight, the total concentration of butadiene in the reaction system being in the range of from about 3 to about 50 per cent by weight, and recovering fromefiiuents of said reaction a material comprising a polycyclic compound containing a furan ring and at least one 18. six-membered carbocyclic ring and containing a carbonyl radical attached to a carbon atom of said furan ring adjacent the oxygen atom thereof.

10. A process for the production of a reaction product of a conjugated diolefin and a furfural, which comprises causing a, conjugated diolefin having not more than '7 carbon atoms per molecule and the formula v I I 4 I HC=C =o-rr where each R is: of: the group consisting of hydrogen and an alkyl group having not more than three carbon atoms per molecule and at least twoare hydrogen, to interact with a furfural having not more than seven carbon atoms per molecule and the formula where each R is of the group consisting of hydroen and methyl and at least one is hydrogen, in the absence of a catalyst, and at a temperature in the range of 160. to 300 F., the said furfural containing water in a; concentration below 10 per cent by weight, and recovering from efiluents of said reaction a product fraction comprising a polycyclic compound containing a furan ring and at least one six-membered carbocyclic ring and containing a carbonyl radical attached to a carbon atom of said furan ring adjacent the oxygen atom thereof.

11. A process for the preparation of a normally liquid aldehydic reaction product containing both a six-membered ring made up wholly of carbon atoms and a five-membered oxygen-containing ring from 1,3-butadiene and furfural which comprises reacting a mixture comprising from 3 to 50 weight per cent 1,3butadiene and from 50 to 97 weight per cent furfural at a temperature within the range of from about 200 F. to about 300 F. for a period of time within the range of from about 5 to about hours, and recovering said normally liquid product from efiiuents of said reaction.

12. A process for the preparation of a normally liquid aldehyde containing both a six-membered ring made up wholly of carbon atoms and a fivemembered oxygen-containing ring from 1,3- butadiene and furfural which comprises reacting a mixture. comprising from 3 to 50 weight per cent 1,3-butadiene and from 50 to 97 weight per cent furfural at a temperature within the range of from about 200 F. to about 300 F., and recovering said normally liquid aldehyde from effluentsof said reaction as a product of the process. i

13. A process for the preparation of it normally liquid aldehyde material which comprises reacting a mixture consisting of from 3 to 50 weight per cent 1,3-butadiene and from 50-97 weight percent furfural containing approximately 5 weight per cent water at a temperature within the range of from about 200 F. to about 300 F., and recovering from eiiluents of said reaction a liquid aldehyde so produced.

14. The process of producing an aldehyde reactionproduct from 1,3-butadiene and furfural, which comprises reacting a mixture consisting essentially of 1,3-butadiene and furfurai, and re covering from eiiluents of said reacting an aldehyde fraction having a boiling point within the range from about 200 to 320 F. at an absolute 19 pressure of one millimeter of mercury, a refractive index at 25 C. within the range of about 1.520 to about 1.530 and a specific gravity at 20 C. within the range of about 1.03 to 1.16.

15. A process for the production of a reaction product of 1,3-butadiene and furfural, which comprises causing 1,3-butadiene to interact with furfural in the absence of a catalyst and at a temperature in the range of 160 to 300 F., said furfural containing water in a concentration below per cent by weight, the total concentration of butadiene in the reaction system being in the range of from about 3 to about 50 per cent by weight, and recovering from efiluents of said reaction a material comprising a polycyclic compound containing a furan ring and at least one six-membered carbocyclic ring and containing a carboxyl radical attached to a carbon atom of said furan ring adjacent the oxygen atom thereof, and recovering also from effluents of said reaction of lactone characterized by the empirical formula C9H12Os as an additional product of the process.

16. A process for the production of a reaction product of a conjugated diolefin and a furfural, which comprises reacting together a conjugated diolefin having not more than '7 carbon atoms per molcule and the formula where each R is of the group consisting of hydrogen and an alkyl group having not more than three carbon atoms per molecule and at least two are hydrogen, and a furfural having not more than seven carbon atoms per molecule and the formula where each R is of the group consisting of hydrogen and methyl and at least one is hydrogen, in the absence of a catalyst, and at a temperature in the range of 160 to 300 F., the resulting reaction mixture containing water in a concentration below 10 per cent by weight based on furfural therein, and recovering from effluents of said reaction a product fraction comprising a polycyclic compound containing a furan ring and at least one siX-membered carbocyclic ring and containing a carbonyl radical attached to a carbon atom of said furan ring adjacent the oxygen atom thereof, and recovering also from effluents of said reaction a lactone characterized by the empirical formula (391-11203 as an additional product of the process.

1'7. A. process for the production of a reaction product of 1,3-butadiene and furfural, which comprises reacting 1,3-butadiene with furfural in the absence of a catalyst and at a temperature in the range of 160 to 300 F., said furfural containing water in a concentration below 10 per cent by weight, the total concentration of butadiene in the reaction system being in the range of from about 3 to about 50 per cent by weight, and recovering a lactone characterized by the empirical formula Cal-11203 from effluents of said reacting as a product of the process.

18. A process for the production of a reaction product of a conjugated diolefin and a furfural, which comprises reacting a mixture consisting essentially of a conjugated diolefin having not more than 7 carbon atoms per molecule and the formula R! R! R! RI H-C= -C=(I3H where each R, is of the grou consisting of hydrogen and an alkyl group having not more than three carbon atoms per molecule and at least two are hydrogen, and a furfural having not more than seven carbon atoms per molcule and the formula where each R. is of the group consisting of hy drogen and methyl and at least one is hydrogen in the absence of a catalyst and at a temperature in the range of 160 to 300 F., the said furfural containing water in a concentration below 10 per cent by weight, and recovering a lactone characterized by the empirical formula Cal-D203 from eflluent of said reaction as a product of the process.

19. A lactone substantially free from other compounds formed during its preparation and having a composition illustrated by the empirical formula Cal-11203 and prepared by the interreaction of butadiene with water and furfural at a temperature within the limits of 160 and 300 F.

20. A process for the production of a lactone from a conjugated diolefin, a furfural, and water, which comprises reacting a mixture consisting essentially of a conjugated diolefin having not more than 7 carbon atoms per molecule and the formula where each R is of the group consisting of hydrogen and an alkyl group having not more than three carbon atoms per molecule and at least two are hydrogen, a furfural having not more than seven carbon atoms per molecule and the formula where each R is of the group consisting of hydrogen and methyl and at least one is hydrogen, and water, at a temperature in the range of to 300 F., the resulting reaction mixture containing water in a concentration below 10 per cent by weight based on furfural therein, and recovering from eliluents of said reaction a lac tone characterized by the empirical formula C'sHizOe, as a product of the process.

21. A composition of matter substantially free from other compounds formed during its preparation and formed by the interreaction of a butadiene with a furfural in the presence of water at a temperature in the range of from l60-300 F., selected from the group consisting of an aldehyde characterized by the formula n-c=o where each R is of the group consisting of hy- References Cited in the file of this patent UNITED STATES PATENTS Name Date Day Nov. 7, 1933 Number Number 22 Name Date Hachmuth June 6, 1944 Hachmuth Apr. 3, 1945 Hachmuth Nov. 26, 1946 Miller Sept. 30, 1947 Schulze; Oct. 18, 1949 Anne Jan. 10, 1950 

1. 2,3,4,5- BIS ($2-BUTENYLENE) -TETRAHYDROFURFURAL SUBSTANTIALLY FREE FROM OTHER COMPOUNDS FORMED DURING ITS PREPARATION. 